If a project is not in an active development state, you can archive it using the Actions menu in the top right of the project settings page. On the Archive project screen, you can choose whether to cancel the builds which are already in the queue using the corresponding option (enabled by default).
By default, permissions to archive projects are given to project and system administrators.
If the parent project of an archived subproject is displayed in the project list (e.g. on the Projects Overview page), the archived subprojects are displayed with the corresponding note.
If you need to dearchive a project, you can do it using the Actions menu in the top right of the project settings page or the More menu next to the project on the Root project settings page.